Interior residential and light commercial foundation systems commonly include cast in place poured concrete slabs and poured concrete or masonry walls supported on cast in place footings.
Typical foundation floors are cast in place slabs resting on cast in place footings.
Framing in metal, both when building out commercial spaces and when erecting entire structures, is becoming more and more common. Probably the best known and most prevalent method of framing in metal involves the use of metal channeling, typically rolled from sheet steel and sometimes aluminum. These metal framing members or studs, often used to erect and reinforce commercial and residential structures, are channels having a substantially U-shaped cross section with a broad base and narrow sides of uniform height. To enhance the stud or framing member's strength and rigidity, the edges of the sides of the U-channel component are bent over to form lips parallel to the plane of the U-channel base to form a C-shaped component.
The outside dimensions of the metal framing members and studs, and the weight or gauge of the member or stud, vary. Typically the members are fabricated to be approximately 4 inches (10 cm) wide by 2 inches (5 cm) deep, corresponding thereby to the width and depth of wood framing and stud members, in which case the lips may extend ¼ to ½ inch (0.63 to 1.3 cm) from the sides of the studs. Eighteen to 20 gauge metal may be used for light gauge, residential construction and commercial wall construction. A heavier range of metal gauge is used in some residential and commercial framing and particularly in multiple story commercial construction.
There has developed a variety of methods for connecting and securing metal frames and wall studs. At the most basic level, metal studs are inserted into and secured within metal tracks by drilling and screwing, from the outside wall of the track into an adjoining metal stud. Similarly, commercially available devices for interconnecting metal framing members, as for example tie brackets, shear connectors and plate connectors, typically use screws and bolts applied from the outside of the track or stud member inwards.
Metal studs and framing members have been modified to include saw or punch slots, tabs and brackets intended to facilitate the interconnection of these studs and framing members to adjoining studs and framing members and/or to cross-bars and other non-framing members that serve to reinforce the studs and framing members. Known connectors, including bracket, plate and tie connectors, presently used to tie together and interconnect metal studs, are generally drilled and screwed on site. Drilling and screwing unsecured connectors pose a safety risk to the worker since the connectors tend to be small and light, and thus easily grabbed and spun by a hand drill.
U.S. Pat. No. 6,799,407 discloses, a system for interconnecting metal framing members, tracks and studs by way of a variety of connectors and tracks. The connectors are specially configured and designed to fit within and interlock with the framing members, tracks and studs. The connectors serve to secure one member, track or stud to another member, track or stud, by fasteners applied from within the connector outwards into the non-surface aspects of the member, track or stud. The tracks are specially configured to interconnect with other tracks or studs using fasteners applied from both the inside out, and the outside in, in three dimensions, while still leaving the surface aspects of tracks and studs free of fastener heads or other protrusions. It employs traditional U-channel shaped framing members or studs, made of sheet steel or aluminum. According to the system, the U-channel members comprise many or all framing components for commercial and residential construction as, for example, wall studs, tracks, headers, hips, floor joists, ceiling joists, roof trusses, fascia, stud blocking, etc.
U.S. Pat. No. 5,687,538 discloses a structural framing member with a C-shaped cross section comprising of a main planar surface and two planar side walls at right angles. The side walls present an inwardly turned lip formed substantially parallel to the base. The capacity of the metal framing joist sections is increased by embossing longitudinal stiffeners perpendicular to the top and bottom side walls, with a minimum depth of 0.01 inch (0.025 cm), continuous along the face of the main planar surface for the full length of the section. By bridging these longitudinal stiffeners with, but not limited to, diagonal embossed stiffeners, a series of adjoining geometric shapes between longitudinal chords has been created to increase the rigidity of the web via adjoining geometric stiffeners which will carry the load by axial deformation rather than pure shear deformation.
U.S. Pat. No. 6,620,487 to Tonyan et al., incorporated herein by reference in its entirety, discloses a reinforced, lightweight, dimensionally stable structural cement panel (SCP) capable of resisting shear loads when fastened to framing equal to or exceeding shear loads provided by plywood or oriented strand board panels. The panels employ a core of a continuous phase resulting from the curing of an aqueous mixture of calcium sulfate alpha hemihydrate, hydraulic cement, an active pozzolan and lime, the continuous phase being reinforced with alkali-resistant glass fibers and containing ceramic microspheres, or a blend of ceramic and polymer microspheres, or, if desired, additional water may be used instead of polymer microspheres to adjust density and nailability (for example by forming the continuous phase from an aqueous mixture having a weight ratio of water-to-reactive powder of 0.6/1 to 0.7/1), or a combination thereof. At least one outer surface of the panels may include a cured continuous phase reinforced with glass fibers and containing sufficient polymer spheres to improve nailability or made with a water-to-reactive powders ratio to provide an effect similar to polymer spheres, or a combination thereof.
U.S. Pat. No. 6,241,815 to Bonen, incorporated herein by reference in its entirety, also discloses formulations useful for SCP panels.
US patent application publication number 2005/0064164 to Dubey et al (U.S. patent application Ser. No. 10/666,294), incorporated herein by reference, discloses a multi-layer process for producing structural cementitious panels (SCP's or SCP panels), and SCP's produced by such a process. After one of an initial deposition of loosely distributed, chopped fibers or a layer of slurry upon a moving web, fibers are deposited upon the slurry layer. An embedment device mixes the recently deposited fibers into the slurry, after which additional layers of slurry, then chopped fibers are added, followed by more embedment. The process is repeated for each layer of the board, as desired.
For use in construction, SCP panels should meet building code standards for shear resistance, load capacity, water-induced expansion and resistance to combustion, as measured by recognized tests, such as ASTM E72, ASTM 661, and ASTM C 1185 or equivalent, as applied to structural plywood sheets. SCP panels are also tested under ASTM E-136 for non-combustibility—plywood does not meet this test.
The panel when tested according to ASTM 661 and American Plywood Association (APA) Test Method S-1 over a span of 16 inches (40.6 cm) on centers, should have an ultimate load capacity greater than 550 lbs (250 kg) under static loading, an ultimate load capacity greater than 400 lbs (182 kg) under impact loading and a deflection of less than 0.078 inches (1.98 mm) under both static and impact loading with a 200 lb (90.9 kg) load.                The racking shear strength of a 0.5 inch (12.7 mm) thick panel measured by the ASTM E72 test using the nail size and spacing described above should be at least 720 lbs/ft (1072 kg/m).        A 4×8 foot, ½ inch thick panel (1.22 m×2.44 m, 12.7 mm thick) should weigh no more than 99 lbs (44.9 kg) and preferably no more than 85 lbs (38.6 kg).        The panel should be capable of being cut with the circular saws used to cut wood.        The panel should be capable of being fastened to framing with nails or screws.        The panel should be machinable so that tongue and groove edges can be produced in the panel.        The panel should be dimensionally stable when exposed to water, i.e., it should expand as little as possible, preferably less than 0.1% as measured by ASTM C 1185.        The panel should not be biodegradable or subject to attack by insects or rot.        The panel should provide a bondable substrate for exterior finish systems.        The panel should be non-combustible as determined by ASTM E136.        After curing for 28 days, the flexural strength of a 0.5 inch (12.7 mm) thick panel having a dry density of no more than 65 to 95 lb/ft3 (1041 to 1520 kg/m3) after being soaked in water for 48 hours should be at least 1700 psi (11.7 MPa), preferably at least 2500 psi (17.2 MPa), as measured by ASTM C 947. The panel should retain at least 75% of its dry strength.        
There is a need for an economical, easy to assemble, durable and non-combustible foundation system.